Open MRI system are known. One such MRI system is disclosed in the U.S. Pat. No. 6,023,165. This prior art MRI has a magnet with opposing poles that create an open MRI imaging area comprising a patient-receiving gap. In one embodiment, a room formed by walls and ceiling and front wall encloses the patient-receiving gap which is between the magnet poles. The legs of a magnet yoke extend through the wall so that the electromagnet is outside of the room housing the gap.
According to another disclosed embodiment in this prior art, the magnet has a C-shaped yoke with the opposing poles creating the patient-receiving gap. A body rest is positioned within the gap and is mounted to pivot between a vertical orientation and a horizontal orientation. A pair of upstanding vertical supports are positioned with the body rest between them. The body rest is mounted on the supports by a pair of pivots. The body rest may also possess a seat to sit a vertically oriented patient.
This prior art also discloses a horizontal platform at the lower end of the body rest that allows a patient to stand on the platform and to lean against the body rest to facilitate patient immobilization within the gap. This arrangement allows for MRI studies of the upright patient where the studies can be performed while the human body, spine, joints, central nervous system and other organs are acted upon by the gravitational field, loading it as it normally loads the upright human body. According to still another embodiment in this prior art, the body rest is situated within a frame and is mounted to pivot about its longitudinal axis. This structure allows the patient to be tilted within the patient-receiving gap. Also disclosed in this prior art is a method of performing magnetic resonance where a patient is positioned in a prone position for receiving magnetic resonance signals while within the patient-receiving gap. The patient's anterior-posterior axis is at an arbitrary angle with respect to the magnetic field that is not zero and not orthogonal.
Another known open MRI system is disclosed in the U.S. Pat. No. 6,404,202. This prior art system has a C-shaped MRI magnet coupled to a pair of opposed ferromagnetic poles that face each other and define a patient-receiving gap. The magnet is positioned on a surface via two support columns. A mobile patient-positioning device has a patient support for positioning the patient for MRI scanning. The patient support is rotatable through a range of orientations. The patient support can be positioned horizontally or in a slanted position. The patient disposed on the mobile patient-positioning can then be moved horizontally into and out of a patient-receiving space in the MRI magnet at a predetermined angle or orientation. Another embodiment of this prior art includes a plurality of patient-positioning devices in which a series of patients can be placed in a ready state while one patient is within the patient-receiving space.
However, there exists a need to improve the known open MRI systems to allow for more flexibility in positioning of patients for examination.